Starch is extensively used in food industry, not only for its energy content (carbohydrates), but also as a thickening or emulsifying agent. Native starches, however, require pre-treatment in order to have the required thickening and similar properties in situ. Starches modified by chemical crosslinking, such as phosphate crosslinking have the required in situ properties, such as shear, acid and heat resistance. However, chemical modification is less desired in food applications, even though some chemical modifications are regarded as safe.
U.S. Pat. No. 6,221,420 discloses a thermally inhibited starch, i.e. a hydrothermally modified starch which is inhibited from returning to its native state. The product is obtained by dehydrating starch to a water level below 1% at a temperature between 100 and 125° C., followed by heat-treating the dry starch at about 140° C., in a fluidized bed. US 2001/0017133 discloses a similar process wherein the starch is also dehydrated at below 125° C. before the inhibition process is started (at 160° C.).
There is a need for providing processes for producing hydrothermally modified starches with improved visco-stability and which are more economical, especially where equipment requirements are concerned.